1. Field of the invention
The present invention relates to double drive shaft motors of a magnetic flux modulation type, to be mounted on hybrid vehicles such as hybrid electric vehicles and used as a drive motor therefor, having an improved structure capable of converting rotation speed and torque of power between two power machines, and for executing an electric power division control such as addition and subtraction of the power.
2. Description of the Related Art
There have been proposed various types of rotary machines capable of converting a high-speed rotation power generated by an internal combustion engine to a low-speed rotation power by gradually changing a transmission gear ratio in a transmission device. For example, Japanese patent No. JP 4505524 discloses a conventional technique of a power machine capable of executing a power transmission on the basis of magnetic gears of a magnetic flux modulation type. The conventional power machine disclosed in Japanese patent No. JP 4505524 has high energy conversion efficiency because of having to convert magnetic flux to current a smaller number of times.
However, the conventional power machine disclosed in Japanese patent No. JP 4505524 has a conventional structure composed of a stator, a magnetic modulation rotor and a field rotor which are coaxially arranged to each other. That is, the stator generates a rotating magnetic field. The magnetic modulation rotor is made of soft magnetic material. The field rotor has permanent magnets. Further, the stator and the field rotor are arranged in a nested structure so that the stator and the field rotor are arranged in a nested structure through the magnetic modulation rotor. This structure limits the size of the field rotor in the conventional power machine, and it becomes difficult to produce a strong field magnetic force.
In addition, when the size of the stator is decreased in order to increase the field magnetic force of the field rotor, this decreases the overall amount of the stator winding wound in the stator, and as a result, decreases the magnitude of generated torque. The generated torque is determined by the product of the field magnetic flux of the field rotor and the amount of the stator winding of the stator.
Still further, it is difficult to adequately fix the soft magnetic material of the magnetic modulation rotor because a magnetic flux penetrates through the soft magnetic material. That is, in addition to the generation of an eddy current in the inside of the soft magnetic material, the soft magnetic material acts as a short-circuit coil in a squirrel-cage induction motor when the outer periphery of the soft magnetic material is fixed by a supporting member made of metal. In order to avoid this drawback, the conventional technique uses a structure in which the soft magnetic material is fixed by an insulation member made of rigid resin or hard resin in order to interrupt a passage of the short-circuit coil. However, the conventional structure using such an insulation member is relatively weakly attached to the magnetic modulation rotor made of the soft magnetic material.
Still further, because the electric rotary machine having the structure previously described has the nested structure of the stator, the magnetic modulation rotor and the field rotor, it is necessary to make a magnetic circuit in an allowable space in which the field rotor is arranged at the innermost position in order to increase the magnetic force. Accordingly, it is difficult to arrange additional members such as bearings and rotation position detection sensors, and further difficult to form any additional space through which cooling air flows in addition to the rotating shaft in the inside of the field rotor in the conventional power machine previously described.